­Many men cringe at the idea of dating women who are more than a few inches taller than they are. Imagine, then, how a man would feel about dating someone 100 times his size.

For the male pillow octopus, being dwarfed by your mate is simply a way of life. Full-grown male pillow octopuses are only a couple of centimeters long and weigh less than a gram. Meanwhile, the females can reach more than six feet (2 meters) and weigh 100 pounds (45.4 kilograms). That means a female is 40,000 times heavier than a male [source: Pickrell].

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In human terms, that would be like a man asking out a woman four times the size of the Statue of Liberty or a woman flirtatiously giving her phone number to a man the size of a beetle. Luckily for the male pillow octopus, however, mating isn't a full contact sport. Males of this species have a modified arm that contains long rows of sperm. He simply tears off this arm and politely hands it to his mammoth female mate, who then saves it for later use.

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­The pillow octopus is just one fascinating example of the octopus order (octopoda), which is as varied as the different plural forms of its name. Octopi, octopods, octopuses and other variations are all used by scientists. Ranging in size from the one-fourth gram male pillow octopus to the record 600 pound (272 kilograms) plus giant Pacific octopus, this most advanced of invertebrates has flabbergasted and amused researchers for years.

In this article, you'll find out why new camera lenses are patterned after the octopus's eye and how a Seattle octopus earned herself the name Lucretia McEvil. But first, let's take a look at the octopus's unique body style.

What creatures live in Earth's oceans? Which are likely to survive into the future? What sorts of sea animals have inhabited the oceans in the past? Finding answers to these questions is the goal of the Census of Marine Life.